Moisture dispensing unit for lithographic fountain system

ABSTRACT

A moisture dispensing unit is provided for use in a roller train supplying fountain solution to a planographic plate of a lithographic printing press. The unit is designed to provide a film of moisture that can be easily controlled as to quantity to meet press requirements of relatively wet or relatively dry to intermediate conditions. In one form, the unit comprises a hard surfaced, hydrophilic roller rotating in a pan of fluid, to carry an unspecified quantity of liquid on its surface from the pan. A moisturemetering elastomeric band extends axially of the roller for substantially the length of the roller and is backed by a reinforcing metal bar or rod. As the roller rotates, the band intercepts the liquid on its surface, shearing away all but a minute surface layer which clings to the roller and clears the metering band as a moisture film to be ultimately transferred to a planographic plate. The amount of moisture in the transferred film is adjusted by varying the pressure and angle by which the band is applied against the film of moisture, preferably by rotating the band about a longitudinal axis. This varies the angle of attack or attitude of the band with respect to the roller and provides different angles of shear. As a result, a variable amount of the moisture film is emitted past the metering band, the remainder of the liquid being turned back.

[451 July 31, 1973 MOISTURE DISPENSING UNIT FOR LITIIOGRAPHIC FOUNTAIN SYSTEM [75] Inventor: Francis K. Lake, Grand Rapids,

Mich.

[73] Assignee: Addressograph-Multigraph Corporation, Cleveland, Ohio [22] Filed: Oct. 20, 1971 [21] Appl. No.: 190,848

Related US. Application Data [63] Continuation of Ser. No. 35,640, May 8, 1970,

abandoned.

[52] US. Cl. 101/148, 101/169 [51] Int. Cl B41f 7/26 [58] Field of Search 101/147, 148, 157, l0l/169, 350, 351, 363-365, 207, 208; 118/261 [56] References Cited UNITED STATES PATENTS 2,359,640 10/1944 Harley 101/365 2,359,770 10/1944 Lundbye 101/157 2,754,796 7/1956 Faulkner, Jr. et al. 118/44 2,945,436 7/1960 Van Buskirk 101/350 3,006,275 10/1961 Allen l0l/l57 3,312,166 4/1967 Gentile l0l/l48 3,343,484 9/1967 Danlgren 101/148 2,704,026 3/1955 Rogge et al 101/157 2,278,138 3/1942 Paardecamp 101/157 FOREIGN PATENTS OR APPLICATIONS 362,131 12/1931 Great Britain 101/148 Primary Ex amiqer-L Reed Fisher Attorney-Russell L. Root and Ray S. Pyle [57] ABSTRACT A moisture dispensing unit is provided for use in a roller train supplying fountain solution to a planographic plate of a lithographic printing press. The unit is designed to provide a film of moisture that can be easily controlled as to quantity to meet press requirements of relatively wet or relatively dry to intermediate conditions.

In one form, the unit comprises a hard surfaced, hydrophilic roller rotating in a pan of fluid, to carry an unspecified quantity of liquid on its surface from the pan. A moisture-metering elastomeric band extends axially of the roller for substantially the length of the roller and is backed by a reinforcing metal bar or rod. As the roller rotates, the band intercepts the liquid on its surface, shearing away all but a minute surface layer which clings to the roller and clears the metering band as a moisture film to be ultimately transferred to a planographic plate. The amount of moisture in the transferred film is adjusted by varying the pressure and angle by which the band is applied against the film of moisture, preferably by rotating the band about a longitudinal axis. This varies the angle of attack or attitude of the band with respect to the roller and provides different angles of shear. As a result, a variable amount of the moisture film is emitted past the metering band, the remainder of the liquid being turned back.

1 Claim, 7 Drawing Figures PATENIEDJUL3 1 I915 SHEET 2 OF 3 PATENTEU JUL3 1 I975 sums or 3 MOISTURE DISPENSING UNIT FOR LITIIOGRAPI-IIC FOUNTAIN SYSTEM RELATED CASES This application is a continuation of my copending application, Ser. No. 35,640, filed May 8, 1970, now abandoned.

BACKGROUND OF THE INVENTION Lithographic printing involves printing from a flat plate having hydrophobic, oleophilic image areas and hydrophilic, oleophobic, nonimage areas. In a nonintegrated system, ink and moisture are separately applied to the planographic plate. For each print made during a run, a planographic plate is alternately dampened with an aqueous fountain solution and inked with a lithographic ink before the print is made. In particular, the fountain solution wets all portions of the surface not covered by a hydrophobic image, while an ink roller deposits ink only on the image areas. The hydrophilic, non-image areas repelling the ink. The ink image may then be transferred directly to a paper sheet or other receptive surface but generally is transferred to a rubber offset blanket which, in turn, transfers the print to the paper sheet.

The moisture train of rollers of a lithographic press includes a roller that is continuously wetted by the liquid of the fountain and transfers the liquid to dampening rollers, usually including at least one fabric covered roller, which eventually spread out the liquid and apply the moisture as a film to a planographic plate. Not only must such a roller continuously carry moisture over its entire surface, but the roller must resist and reject any greasy ink which may be picked up by the dampening rollers from the image areas of the plate. Otherwise,

even a gradual accumulation of ink renders the roller unfit for use and causes loss of press time while it is cleaned or replaced. In one specific type of lithographic printing press, a train of rollers of a moisture fountain comprises, in sequence, a knurled roller, ductor roller, a smooth metal-surfaced rider roller, and a molleton-covered roller. The ductor roller travels back and forth between the knurled roller and the rider roller carrying moisture; and the molleton-covered roller engages the planographic plate.

Fabrics like molleton, which is cotton pile fabric, shed lint and nap which becomes entrapped in the system. The lint and nap migrate throughout the ink and moisture systems, adversely affecting the operation as by appearing as pips or specks on copy, or by plugging the ink flow from the ink fountain, etc. Moreover, it is difficult to tell how much moisture is actually being transferred by a fabric-covered roller, and there is little or no control on the amount of moisture so transferred.

Prior systems either depend upon an interrupted flow, such as by ductors, or metered flow such as by variable speed rollers.

It would, therefore, advance the art to provide a moisture dispensing unit for a lithographic printing press or the like that is not only lint-free but disperses a fine, controllable continuous film of moisture, without the expense of roller systems with separate drives, and operator expertise.

SUMMARY OF THE INVENTION The present invention relates to a moisture dispensing unit for a lithographic printing press. In one form,

the unit comprises essentially two members including a hard surfaced roller and a metering or wiping bar having a substantially flat, elastomeric band adhered to one side of the bar and disposed toward the roller. The thickness of the band is not critical. The surface of the roller is sufficiently hydrophilic to attract and retain a layer of moisture that is greater in thickness than any film of moisture to be ultimately transferred to a press. The elastomeric layer contains particles of uniformly dispersed solid lubricant as a filler. These particles aid in a metering action hereinafter described and also prevent seizure between the metering bar and the roller should it inadvertently become dry.

Because of the hydrophilic character of the roller, it readily receives and tenaciously retains a layer of fluid which literally clings to the roller. The metering bar is so positioned with respect to the roller, that the elastomeric band intercepts and shears the layer down to a film of moisture on the roller as it rotates. Although the shear action provided by the elastomeric band penetrates the moisture film to an extent to provide a damming effect, the metering bar and elastomeric band cannot sweep the hydrophilic roller entirely free of moisture. The effect of the shearing action reaches a terminal or boundary layer shear, that is, it removes moisture from a roller up to an extremely fine, substantially mono molecular film, but it cannot remove all of the moisture film.

By adjusting the pressure of the elastomeric band on the moisture film, the quantity of the film emitted past the metering bar is regulated to meet diverse requirements. The pressure is adjusted by rotating the metering bar about a longitudinal axis; and/or by resiliently pressing the metering bar and roller together and varying the force of such pressure. Rotation of the bar is preferred since it produces different angles of shear with greater degree of control on the amount of moisture emitted by the roller past the metering bar.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. l is a schematic view of a lithographic printing press showing the environmental use of the present moisture dispensing unit in combination with an inking system, the latter being illustrated only in part;

FIGS. 2 and 3 are enlarged schematic views of a fountain roller and metering bar of the present invention in which two adjusted, rotative positions of the metering bar are shown;

FIG. 41 is a perspective view of one form of the dispensing unit;

FIG. 5 is a transverse section of FIG. 4 on the line 5-5;

FIG. 6 is a transverse section of an attitude control device taken from FIG. 4 on the line 6-6; and

FIG. 7 is a top plan of the attitude control device of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 schematically illustrates the general environment of a lithographic press. A plate cylinder 10 has a moisture train of rollers including a form roller 11 contacting a fountain roller 112 having a moisture-metering bar 13, the roller 12 and metering bar 13 constituting a moisture dispensing unti of the present invention. Only two rollers M and of the inking train are shown, it being understood that the inking apparatus used to apply ink to a planographic plate on cylinder does not form a part of the present invention and may embody any known, conventional structure.

FIGS. 4 and 5 illustrate one embodiment of the moisture dispensing unit. A pair of spaced end plates 16 and 17 support the unit and attendant equipment. The fountain roller 12 has end stub shafts l8 joumalled for rotation in the end plates. Roller 12 is hard surfaced and has a hydrophilic character to attract and retain a layer of moisture. Preferably, roller 12 has a metal surface to provide these properties, such as a surface of chromium, tin-nickel alloy, or the like. Form roller 11 of conventional construction is also joumalled for rotation in the end plates 16 and 17 and contacts fountain roller 12 as shown in FIG. 5 to provide a desired area of contact of about three thirty-seconds to about five thirty-seconds of an inch wide along the length of the rollers. The form roller 11 has relatively soft surface rubber to assist it in conforming with a planographic plate. Threaded fasteners 20 pass through openings at the ends of a moisture trough 21. The trough 21 embraces a bottom portion of the fountain roller 12 to supply fountain solution and has an inlet 22 to which a moisture supply hose and reservoir (not shown) are attached to fill the trough and conventionally maintain the solution at a predetermined level.

The metering bar 13 of substantially rectangular cross section has an elastomeric layer 23 adhered to one side facing the roller 12. Preferably the layer 23 is coextensive with the side of the bar to which it is adhered. End plates 16 and 17 have open ended slots 24 to receive stub shafts 25 extending from the ends of the metering bar 13 to enable the bar to move toward and away from the roller 12 to meet the exigencies of the situation as the bar 13 is pressed toward the roller and- /or rotated about a longitudinal axis as hereinafter described. A bolt 26 secures a pointer 27 to one of the stub shafts 25 of the metering bar. The pointer cooperates with a scale or indicia 28 on the side of end plate 16 to indicate the relative rotative position of the bar 13.

Molded nitrile rubber has been found to be well suited for forming the elastomer of the layer 23, that is, rubber produced by copolymerizing an unsaturated nitrile with a diene. A copolymer of acrylonitrile and butadiene is preferred. To facilitate the shearing action of the layer 23 on a film of moisture and to prevencthe layer from grabbing or seizing the roller should it become dry, the layer 23 contains dispersed particles of solid lubricant. Such dry operation would otherwise permit crazing of the layer 23. The size and amount of such particles are not critical. They may range from submicron size to about 20 mesh U. S. standard sieve and constitute from about 5 percent to about 20 per cent by weight of the layer 23. The solid particles may comprise clay, such as China or kaolin or other like silicates. The particles are milled and uniformly dispersed in the elastomer prior to molding.

The preferred embodiment of this invention provides a flat resilient pad pressed against the surface of roller 12. The metering capability of the pad is variable within limits by a variation of pressure. The limits are real and limited, because mere increase of pressure will cause excess pressure on bearinsg, and such pressure may cause a condition wherein a sudden complete cutoff of moisture occurs.

Therefore, a second adjustment capability is provided by tipping the pad away from its tangent attitude. This tipping causes a shear action, with better lubricaton properties, which is finely tuned to the needed moisture film condition by altering both the angle and pressure.

The illustrated embodiment centers about a cross bar 30 mounted to side plates 16 and 17 by keeper bars 31. The bar 30 is held snug in keeper bars 31 by flat head bolts 32.

The pressure applied to bar 13 is preferably resilient to compensate for foreign matter inadvertently trapped, and to reduce the requirement for precision pressure devices. Two angled lugs 40 are joumalled on cross bar 30. Each lug has a spring wire 46 projecting to the bar 13. An arm 43 associated with each lug 40, isjournalled on bar 30. The arms 43 have rounded ends 44 which ride the top of the bar 13. Two pins 45 vertically spaced on each end 44 enable the springs 46 to transfer pressure to the rounded ends 44 for better application of pressure to the bar 13.

As best seen in FIG. 5, pressure is applied to the spring wires 46 by forcing the lugs 40 to pivot about rod 30. Lugs 40 have a rear extension, and each carries a thumb bolt 41. Each bolt 41 bears against a bearing bar 42. As the bolts 41 are threaded to bear against bar 42, lugs 40 turn clockwise in FIG. 5, and press the spring wires 46 toward the bar 13. The degree of pressure, within limits of the selected spring wire 46, is selected individually by each bolt 41.

If the desired metering of moisture is not obtained by mere pressure, the rod 13 may be tilted away from its essentially tangent position shown in FIG. 2, to an angled position, such for example as shown in FIG. 3.

The greater the rotation of rod 13, the greater the attitude angle becomes with respect to the roller surface. Then, together with the variable pressure described, a great selection of angle and pressure combinations are available to the operator for obtaining the best fluid film metering conditions.

Tilting of rod 13 is obtained simply and efficiently by the attitude control device shown in detail in FIGS. 6 and 7. A nut member 33 is joumalled on rod 30 substantially midway between side plates 16 and 17. A rod 34 extends from member 33 to a block end 36. Rod 13 carries a ball head pin 38. Block 36 has a key slot opening 37 and is composed of stiff resilient composition material. The ball end of pin 38 may be forced into opening 37, and will be held there with considerable force, but the block 36 and ball end are not rigidly connected. A considerable degree of flexibility is possible. Thus, a very inexpensive ball joint interconnection is produced.

The end of rod 34 opposite block 36 is anchored in nut member 33 and fitted with a drive turning wheel 35. Wheel 35 has a hub 35A circumscribed by a channel 39. A pin 39A carried by member 33 projects into the channel and locks wheel 35 against longitudinal movement, but permits rotation.

The end of rod 34! is flattened and projects into a slot in the rear of member 33 to prevent rotation of the rod 34.

By turning wheel 35, rod 34 is driven toward or away from rod 13, and causes ball pin 38 to drive rod 13 into any operator chosen attitude.

Then, by operation of the thumb bolt 41, a selected pressure is applied to the end areas of rod 13, and the operator is able to control the metering action to a fine degree of selection.

The various rollers of the described embodiment may be driven in any conventional manner. For example, the shaft of the plate cylinder may'have a gear which conventionally drivesthe shaft of the form roller 11 through an Oldham coupling. A coupling gear of the form roller 1 l, in turn, engages and drives a gear on the shaft of the fountain roller 12. The relative directions of rotation of the rollers are shown by arrows in FIG. 1. lt is also understood that the fountain roller 12 may be conventionally axially oscillated for uniformity of moistuer emission. The form roller 11 has standard compound eccentric adjustments, generally indicated at 52 in FIG. 4, on both end plates 16 and 1-7 to control the bear or kiss between the form roller 11 and fountain roller 12.

In operation, as fountain roller 12 rotates it picks up and retains a thick layer of moisture from trough 21. The metering bar 13 is so positioned that the elastomeric layer 23 shears away and turns back an outermost cut of the layer but not all of it. A film of moisture must be retained, otherwise, if the elastomer of layer 23 touched the fountain roller 12, the result would be that of a squeegee action, much like a rubber bladed wiper on the windshield of an automobile.

FIG. 2 schematically illustrates the relative positions of a metering bar 13 and roller 12 when the bar approaches the roller on a line which passes through the longitudinal center of the bar and is radial with respect to the center of the roller 12. The resultant of all the forces acting in the system causes some slight deformation of the elastomer of layer 23. The actual amount of deformation has not been found to be relevant. However, while the inventiois not limited to theory, it does appear that varying the pressure of layer 23 against the film of moisture on roller 12 affects the quantity of moisture emitted by the roller 12 past the metering bar 13.

For instance, the angle of attack or attitude of the metering bar 13 and its elastomeric layer 23 has been found toeffect materially the amount of moisture emitted by the fountain roller 12 past the bar 13. The relative positions illustrated by FIG. 2 produces the least interference with a film of misture and accordingly the largest amount of moisture passes the metering bar. If

the bar 113 is rotated counterclockwise as viewed in FIG. 2 to the position of FIG. 3 (that is, against the direction of rotation of roller 12), the angle of shear is increased with the result that a less amount of moisture of moisture escaping between the layer 23 and roller 12. Increasing the pressure reduces the emission rate. Turning the adjustable'belts 41 clockwise as viewed in perspective in FIG. 4 presses the curved ends 44 of the arms 43 with greater force against the bar 13. This greater force in turn is transmitted to the layer 23 and then to the film of moisture on the roller 12. Conversely, turning the bolts counterclockwise as viewed in FIG. 4 releases some of the pressure on the curved ends d4 against the bar 13, thereby increasing the emission rate beneath the layer 23. The pressure exerted by the arms 43 also serves to stabilize the action of the meter ing bar 13 on a film of moisture, particularly at relatively high roller surface speeds.

Athough it is preferred to use the fountain roller 12 as a hard surfaced hydrophilic roller with the metering bar 13 having an elastomeric layer 23, as described, it is understood that these parts may be reversed within the contemplation of the invention, and the thickness of layer 23 may be increased to any dimension, as long as it is dimensionally stabilized such as by supporting structure. That is, the fountain roller may be elastomeric but hydrophilic, and the metering bar may be a hard surfaced, shearing metallic band.

In addition to avoiding fabric covered-rollers and the shedding of lint and nap, the present moisture dispensing unit is of simple construction involving but two rollers. The tilting blade acts as a selection fluid shearing device whereby continuous films of moisture of varying minute thicknesses can be flowed to a planographic plate and satisfy different demands of operation.

While the foregoing discloses a presently preferred embodiment, it is understood that the invention may be practiced in still other forms within the scope of the following claims.

What is claimed is:

l. A moisture dispensing unit for a lithographic printing press comprising:

a hard surfaced roller adapted to be rotatably mounted and to receive liquid to be transferred, said hard surface being sufficiently hydrophilic to attract and retain a layer of such liquid;

moisture-metering means extending axially of the roller including a rod, one face of which is constituted by a substantially flat, wear resistant, continuous elastomeric band positioned in contact with said roller surface over substantially the entire roller length to intercept said layer of moisture;

- frame means at each end of the rod providing guide slots floatingly permitting rocking motion of the bar and confining its bodily motion to a path towards and away from said roller in a direction substantially radially thereof;

spring means urging said rod bodily towards said roller;

means for adjusting the loading applied by said spring means to said rod; and

screw means for adjustably rocking said rod about its longitudinal axis, and for holding the same in any desired rocked position, regardless of the radial location of the rod relative to the axis of said roller.

3' l l l W UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,7 -9,Ol2 Dated July 3 973 Invent flq) FRANCIS K. LAKE It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown' below:

Column 1, Line 20, "areas. The" should read "areas, the".

Column 2, Line 66, "unti" should read unit" Column 3, Line l-8, "prevencthe" should read prevent the" Column 3, Line 65, "bearinsg" should read "bearings";

Column 5, Line 13, "moistuer" should read "moisture".

Column 5, Line 16, "bear" should read "bead" Column 5, Line 35, inventiois" should read invention is" Column 5, Line T5, "misture" should read "moisture" Column 5, Line 56, "vaires" should read "varies" I Column 6, Line 12, though" should read lthough" Signed and sealed this 18th day of June 1971;.

(SEAL) Attest:

EDWARD M.FLE'1'OHER, JR C MARSHALL. DANN Attesting Officer Commissioner of Patents F ORM PO-1050' (IO-69) USCOMM'DC 6O376-P69 US. GOVERNMENT PRINTING OFFICE: I969 0-366-330 

1. A moisture dispensing unit for a lithographic printing press comprising: a hard surfaced roller adapted to be rotatably mounted and to receive liquid to be transferred, said hard surface being sufficiently hydrophilic to attract and retain a layer of such liquid; moisture-metering means extending axially of the roller including a rod, one face of which is constituted by a substantially flat, wear resistant, continuous elastomeric band positioned in contact with said roller surface over substantially the entire roller length to intercept said layer of moisture; frame means at each end of the rod providing guide slots floatingly permitting rocking motion of the bar and confining its bodily motion to a path towards and away from said roller in a direction substantially radially thereof; spring means urging said rod bodily towards said roller; means for adjusting the loading applied by said spring means to said rod; and screw means for adjustably rocking said rod about its longitudinal axis, and for holding the same in any desired rocked position, regardless of the radial location of the rod relative to the axis of said roller. 